Data flow affinity for heterogenous virtual machines

ABSTRACT

According to one aspect of the present disclosure, a method and technique for data flow affinity for heterogeneous virtual machines is disclosed. The method includes: connecting first and second logical partitions to a shared virtual adapter, the first logical partition having a maximum receive unit (MRU) different than a MRU of the second logical partition; and responsive to receiving data by the shared virtual adapter destined for the first or second logical partitions, performing transmission control protocol (TCP) segmentation offload processing of the data by the shared virtual adapter utilizing the MRU of the first logical partition as the transmission unit for data destined for the first logical partition and utilizing the MRU of the second logical partition as the transmission unit for data destined for the second logical partition.

BACKGROUND

A virtual machine is a virtual sharing or partitioning of computerresources. For example, the virtually partitioned resources may includeone or more processors, memory, storage, network cards, etc. Eachvirtual machine may run its own instance of an operating system and mayrun one or more applications on its operating system. The virtualmachines may have separate file systems, separate users, separateapplications, and separate processes. The virtual machines are generallyseparate, or isolated, from each other in some ways, thereby providing alook and feel like a separate server or machine from the perspective ofits users. A virtual input/output (I/O) server generally provides I/Oprocessing for the different virtual machines to bridge communicationsbetween a physical network adapter and each of the virtual machines.

BRIEF SUMMARY

According to one aspect of the present disclosure a method and techniquefor data flow affinity for heterogeneous virtual machines is disclosed.The method includes: connecting first and second logical partitions to ashared virtual adapter, the first logical partition having a maximumreceive unit (MRU) different than a MRU of the second logical partition;and responsive to receiving data by the shared virtual adapter destinedfor the first or second logical partitions, performing transmissioncontrol protocol (TCP) segmentation offload processing of the data bythe shared virtual adapter utilizing the MRU of the first logicalpartition as the transmission unit for data destined for the firstlogical partition and utilizing the MRU of the second logical partitionas the transmission unit for data destined for the second logicalpartition.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a more complete understanding of the present application, theobjects and advantages thereof, reference is now made to the followingdescriptions taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an embodiment of a network of data processing systems in whichthe illustrative embodiments of the present disclosure may beimplemented;

FIG. 2 is an embodiment of a data processing system in which theillustrative embodiments of the present disclosure may be implemented;

FIG. 3 is a diagram illustrating an embodiment of a data processingsystem for data flow affinity for heterogeneous virtual machines inwhich illustrative embodiments of the present disclosure may beimplemented; and

FIG. 4 is a flow diagram illustrating an embodiment of a method for dataflow affinity for heterogeneous virtual machines according to thepresent disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide a method and technique fordata flow affinity for heterogeneous virtual machines. For example, insome embodiments, the method and technique includes: connecting firstand second logical partitions to a shared virtual adapter, the firstlogical partition having a maximum receive unit (MRU) different than aMRU of the second logical partition; and responsive to receiving data bythe shared virtual adapter destined for the first or second logicalpartitions, performing transmission control protocol (TCP) segmentationoffload processing of the data by the shared virtual adapter utilizingthe MRU of the first logical partition as the transmission unit for datadestined for the first logical partition and utilizing the MRU of thesecond logical partition as the transmission unit for data destined forthe second logical partition. Embodiments of the present disclosureenable better and/or full utilization of virtual machine bandwidthcapabilities by tailoring the packet sizes destined for the respectivevirtual machines according to the bandwidth capacity of the respectivevirtual machines. For example, embodiments of the present disclosureutilize a shared virtual adapter to custom-fit the packet sizescommunicated to a respective virtual machine based on the maximumreceive unit (MRU) of the respective virtual machine. The shared virtualadapter is configured to perform software-based large receive offload(LRO) processing of the incoming data packets based on the MRU for thevirtual machine destination. The aggregated data packets may then becommunicated to the virtual machine destination (e.g., usingtransmission control protocol (TCP) segmentation offload (TSO)processing) using the MRU for the respective virtual machine as thetransmission unit.

As will be appreciated by one skilled in the art, aspects of the presentdisclosure may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present disclosure may take theform of an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system.”Furthermore, aspects of the present disclosure may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer usable or computer readablemedium(s) may be utilized. The computer readable medium may be acomputer readable signal medium or a computer readable storage medium. Acomputer readable storage medium may be, for example but not limited to,an electronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, or device, or any suitable combinationof the foregoing. More specific examples (a non-exhaustive list) of thecomputer readable storage medium would include the following: anelectrical connection having one or more wires, a portable computerdiskette, a hard disk, a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flashmemory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or anysuitable combination of the foregoing. In the context of this document,a computer readable storage medium may be any tangible medium that cancontain, or store a program for use by or in connection with aninstruction execution system, apparatus or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present disclosure are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of thedisclosure. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in acomputer-readable medium that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions which execute on the computer or other programmableapparatus provide processes for implementing the functions/actsspecified in the flowchart and/or block diagram block or blocks.

With reference now to the Figures and in particular with reference toFIGS. 1-2, exemplary diagrams of data processing environments areprovided in which illustrative embodiments of the present disclosure maybe implemented. It should be appreciated that FIGS. 1-2 are onlyexemplary and are not intended to assert or imply any limitation withregard to the environments in which different embodiments may beimplemented. Many modifications to the depicted environments may bemade.

FIG. 1 is a pictorial representation of a network of data processingsystems in which illustrative embodiments of the present disclosure maybe implemented. Network data processing system 100 is a network ofcomputers in which the illustrative embodiments of the presentdisclosure may be implemented. Network data processing system 100contains network 130, which is the medium used to provide communicationslinks between various devices and computers connected together withinnetwork data processing system 100. Network 130 may include connections,such as wire, wireless communication links, or fiber optic cables.

In some embodiments, server 140 and server 150 connect to network 130along with data store 160. Server 140 and server 150 may be, forexample, IBM System p® servers. In addition, clients 110 and 120 connectto network 130. Clients 110 and 120 may be, for example, personalcomputers or network computers. In the depicted example, server 140provides data and/or services such as, but not limited to, data files,operating system images, and applications to clients 110 and 120.Network data processing system 100 may include additional servers,clients, and other devices.

In the depicted example, network data processing system 100 is theInternet with network 130 representing a worldwide collection ofnetworks and gateways that use the Transmission ControlProtocol/Internet Protocol (TCP/IP) suite of protocols to communicatewith one another. At the heart of the Internet is a backbone ofhigh-speed data communication lines between major nodes or hostcomputers, consisting of thousands of commercial, governmental,educational and other computer systems that route data and messages. Ofcourse, network data processing system 100 also may be implemented as anumber of different types of networks, such as for example, an intranet,a local area network (LAN), or a wide area network (WAN). FIG. 1 isintended as an example, and not as an architectural limitation for thedifferent illustrative embodiments.

FIG. 2 is an embodiment of a data processing system 200 such as, but notlimited to, client 110 and/or server 140 in which an embodiment of asystem for data flow affinity for heterogeneous virtual machinesaccording to the present disclosure may be implemented. In thisembodiment, data processing system 200 includes a bus or communicationsfabric 202, which provides communications between processor unit 204,memory 206, persistent storage 208, communications unit 210,input/output (I/O) unit 212, and display 214.

Processor unit 204 serves to execute instructions for software that maybe loaded into memory 206. Processor unit 204 may be a set of one ormore processors or may be a multi-processor core, depending on theparticular implementation. Further, processor unit 204 may beimplemented using one or more heterogeneous processor systems in which amain processor is present with secondary processors on a single chip. Asanother illustrative example, processor unit 204 may be a symmetricmulti-processor system containing multiple processors of the same type.

In some embodiments, memory 206 may be a random access memory or anyother suitable volatile or non-volatile storage device. Persistentstorage 208 may take various forms depending on the particularimplementation. For example, persistent storage 208 may contain one ormore components or devices. Persistent storage 208 may be a hard drive,a flash memory, a rewritable optical disk, a rewritable magnetic tape,or some combination of the above. The media used by persistent storage208 also may be removable such as, but not limited to, a removable harddrive.

Communications unit 210 provides for communications with other dataprocessing systems or devices. In these examples, communications unit210 is a network interface card. Modems, cable modem and Ethernet cardsare just a few of the currently available types of network interfaceadapters. Communications unit 210 may provide communications through theuse of either or both physical and wireless communications links.

Input/output unit 212 enables input and output of data with otherdevices that may be connected to data processing system 200. In someembodiments, input/output unit 212 may provide a connection for userinput through a keyboard and mouse. Further, input/output unit 212 maysend output to a printer. Display 214 provides a mechanism to displayinformation to a user.

Instructions for the operating system and applications or programs arelocated on persistent storage 208. These instructions may be loaded intomemory 206 for execution by processor unit 204. The processes of thedifferent embodiments may be performed by processor unit 204 usingcomputer implemented instructions, which may be located in a memory,such as memory 206. These instructions are referred to as program code,computer usable program code, or computer readable program code that maybe read and executed by a processor in processor unit 204. The programcode in the different embodiments may be embodied on different physicalor tangible computer readable media, such as memory 206 or persistentstorage 208.

Program code 216 is located in a functional form on computer readablemedia 218 that is selectively removable and may be loaded onto ortransferred to data processing system 200 for execution by processorunit 204. Program code 216 and computer readable media 218 form computerprogram product 220 in these examples. In one example, computer readablemedia 218 may be in a tangible form, such as, for example, an optical ormagnetic disc that is inserted or placed into a drive or other devicethat is part of persistent storage 208 for transfer onto a storagedevice, such as a hard drive that is part of persistent storage 208. Ina tangible form, computer readable media 218 also may take the form of apersistent storage, such as a hard drive, a thumb drive, or a flashmemory that is connected to data processing system 200. The tangibleform of computer readable media 218 is also referred to as computerrecordable storage media. In some instances, computer readable media 218may not be removable.

Alternatively, program code 216 may be transferred to data processingsystem 200 from computer readable media 218 through a communicationslink to communications unit 210 and/or through a connection toinput/output unit 212. The communications link and/or the connection maybe physical or wireless in the illustrative examples.

The different components illustrated for data processing system 200 arenot meant to provide architectural limitations to the manner in whichdifferent embodiments may be implemented. The different illustrativeembodiments may be implemented in a data processing system includingcomponents in addition to or in place of those illustrated for dataprocessing system 200. Other components shown in FIG. 2 can be variedfrom the illustrative examples shown. For example, a storage device indata processing system 200 is any hardware apparatus that may storedata. Memory 206, persistent storage 208, and computer readable media218 are examples of storage devices in a tangible form.

FIG. 3 is an illustrative embodiment of a system 300 for data flowaffinity for heterogeneous virtual machines. System 300 may beimplemented on data processing systems or platforms such as, but notlimited to, servers 140 and/or 150, clients 110 and/or 120, or at otherdata processing system locations. In the embodiment illustrated in FIG.3, processors, memory, and other hardware resources of computer system300 may be apportioned into logical partitions (LPARs) 310 that mayoperate independently, each LPAR 310 running its own operating systemand applications. In the illustrated embodiment, LPARs 310 include LPARs310 ₁, 310 ₂ and 310 ₃; however, it should be understood that a greateror fewer quantity of LPARs 310 may be provisioned. LPARs are assigned asubset of a computer's physical layer hardware resources 320 (i.e., asubset of the hardware underlying the server environment) and arevirtualized within the server environment as a separate computer/virtualmachine. Resources such as processor capacity, memory, or any other typeof resource may be assigned to a particular LPAR. Each LPAR has its ownvirtual operating system (OS) instance (e.g., operating systems 330, 332and 334 in respective LPARs 310 ₁, 310 ₂ and 310 ₃) and associatedfiles, allowing for multiple operating systems to be simultaneouslyexecuting within the server environment.

In the embodiment illustrated in FIG. 3, a physical input/output (I/O)adapter 338 in physical layer 320 is assigned/configured to be shared bya plurality of LPARs 310 via an LPAR 340 that is dedicated toimplementing I/O functionality by executing virtual I/O server (VIOS)software. The LPAR 340 running the VIOS software may be referred toherein as a VIOS LPAR or VIOS partition 340. Likewise, the executingVIOS software, which provides VIOS functionality, may be referred toherein as a VIOS. Logical partitioning is facilitated by software 342 (a“hypervisor”) that controls the computer system's hardware and monitorsthe operating systems of the LPARs. Hypervisor 342 operates at a levelbetween the logical partition operating systems level and computersystem 300 hardware at a physical layer 320. Hypervisor 342 may rundirectly on the computer system's hardware 320 or within a conventionaloperating system environment, depending upon the implementation.

One way of enabling Internet protocol-based communication among LPARswithin the same computer system is by software-based, virtual adapters346 (e.g., virtual Ethernet adapters) provided by hypervisor 342.Virtual adapters are provided for LPARs 310 ₁, 310 ₂ and 310 ₃ (referredto as VEA₁ 346 ₁, VEA₂ 346 ₂ and VEA₃ 346 ₃, respectively, in FIG. 3).In the illustrated embodiment, the VIOS also enables logical partitionsto also communicate with external (i.e., remote) computer systems over acommunication network 348 using a virtual, shared adapter 350 (e.g., avirtual shared Ethernet adapter), functionality for which is provided bythe operating system of VIOS LPAR 340. Adapter 350 may be software thatruns on VIOS LPAR 340 and that bridges: i) a real (i.e., physical)adapter 338 (e.g., an Ethernet adapter), which is coupled to an externalnetwork 348 of computer systems; and ii) one or more virtual adapters346 for LPARs 310. Using a shared virtual adapter 350 in the VIOS LPAR340, LPARs 310 share access to the physical network and communicate withexternal computer systems and logical partitions on those computersystems.

In some embodiments, some LPARs 310 may have different data receivingproperties depending on the operating system running on the particularLPAR 310, thereby resulting in a heterogeneous virtual machineenvironment. For example, OS 330 may have a maximum receive unit (MRU)of 64 KB (e.g., when software-based large receive offload (LRO) isenabled), while OS 332 may not support software-based LRO (e.g., havinga MRU of 9 KB). LRO is a technique for increasing inbound throughput ofnetwork connections by aggregating multiple incoming packets into abuffer before passing the data onward. OS 334 may also have a differentMRU. Typically, to accommodate different MRUs between different LPARs, alowest common MRU may be used to communicate data from adapter 350 toLPARS 310. Embodiments of the present disclosure enable a LPAR'sbandwidth to be better/fully utilized by custom-fitting the data packetsizes according to the LPAR 310 capabilities.

In the embodiment illustrated in FIG. 3, adapter 350 includes LRO logic360 and MRU logic 362. LRO logic and MRU logic 362 are configured toaccommodate differing data packet receiving properties corresponding todifferent LPARs 310. LRO logic 360 and/or MRU logic 362 may comprisesoftware, logic and/or executable code for performing various functionsas described herein (e.g., residing as software and/or an algorithmrunning on a processor unit, hardware logic residing in a processor orother type of logic chip, centralized in a single integrated circuit ordistributed among different chips in a data processing system). In someembodiments, MRU logic 362 is configured to determine/identify a MRU fora particular LPAR 310 such that LRO logic 360 may perform large receiveoffload processing of the incoming data packets up to the MRU for arespective LPAR 310. LRO logic 360 may then perform transmission controlprotocol (TCP) segmentation offload (TSO) processing of the data packetsto a respective LPAR 310 using the MRU as the transmission unit.

In some embodiments, LRO may be disabled in physical adapter 338 (e.g.,by a user/administrator or by logic 360/362) to prevent LRO dataprocessing in connection with LPARs not supporting LRO. To connect aparticular LPAR 310 to adapter 350, an address resolution protocol (ARP)exchange is implemented/performed between adapter 350 and a respectivevirtual adapter 346 for the respective LPAR 310 to determine/assign aparticular media access control (MAC) address to the respective virtualadapter 346 internet protocol (IP) address. In some embodiments, anextra flag/field is included in the ARP response packet from therespective virtual adapter 346 indicating the MRU for the respectiveLPAR 310. During the ARP message exchange, adapter 350 is configured toparse the ARP response packet(s) and read the designated MRU flag/fieldto identify the MRU for the respective LPAR 310 (e.g., via logic 360).However, it should be understood that other methods may be used toidentify the MRU for a particular LPAR 310 (e.g., based on anidentification of the operating system running in the particular LPAR310, data stored by hypervisor 342 upon LPAR 310 provisioning, etc.).Logic 360 of adapter 350 my then store the MRU for each respective LPAR310 as MRU data 370 (e.g., as a relational database or otherwise). Forexample, in the illustrated embodiment, MRU data 370 includes adestination MAC address (DMAC) 372 for each respective LPAR 310 (e.g.,DMAC₁ for LPAR 310 ₁, DMAC₂ for LPAR 310 ₂, etc.). MRU data 370 alsoincludes the MRU 374 for each respective LPAR 310 (e.g., MRU₁ for LPAR310 ₁, MRU₂ for LPAR 310 ₂, etc.).

In response to adapter 350 receiving incoming data packets, adapter 350parses the incoming data packets to determine a destination address(DMAC) for the respective data packets. In response to adapter 350identifying the destination address(es) for the incoming data packets ascorresponding to a particular LPAR 310 connected to adapter 350, adapter350 accesses MRU data 370 (e.g., via logic 360) to identify/determine aMRU for the respective destination LPAR 310. Adapter 350 then performsLRO processing of the data packets by aggregating the data packetsdestined for a particular LPAR 310 up to the MRU for the respectivedestination LPAR 310 via LRO logic 360 and forwards the data packets tothe destination LPAR 310 using TSO using the identified MRU as thetransmission unit in the transfer operation.

FIG. 4 is a flow diagram illustrating an embodiment of a method for dataflow affinity for heterogeneous virtual machines. The method begins atblock 402, where LRO is disabled in physical adapter 338. At block 404,connection of one or more LPARs 310 to shared virtual adapter 350 isinitiated. At block 406, the MRU value for a respective LPAR 310connecting with shared virtual adapter 350 through an ARP communicationexchange is attached/included in an ARP response packet. At block 408,the shared virtual adapter 350 parses the ARP response packet andidentifies the MRU for the respective LPAR 310. At block 410, sharedvirtual adapter 350 stores the MRU value for the respective LPAR 310correlated to the MAC address of the respective LPAR 310.

At block 412, shared virtual adapter 350 receives incoming data packets(e.g., from network 348). At block 414, shared virtual adapter 350parses the incoming data packets to identify a destination address forthe communications. At decisional block 418, a determination is made byshared virtual adapter 350 (e.g., via MRU logic 362) whether theidentified destination address for the incoming data packets correspondsto an LPAR 310 connected to shared virtual adapter 350. For example, MRUlogic 362 may be configured to compare the destination address parsedfrom the incoming data packets with information stored as MRU data 370to determine whether MRU data 370 reflects a corresponding/matching MACaddress. If not, the method proceeds to block 424, where the incomingdata packets may be forwarded/transmitted the indicated destinationusing TSO or other applicable protocol. If it is determined atdecisional block 418 that the destination address parsed from theincoming data packets matches a MAC address stored as MRU data 370, themethod proceeds to block 420, where MRU logic 362 acquires and/orotherwise identifies the MRU for the LPAR 310 with the matching MACaddress. At block 422, LRO logic 360 of shared virtual adapter 350performs LRO aggregation and buffering of the incoming data packets upto the identified MRU for the destination LPAR 310. The method thenproceeds to block 424, where the aggregated data packets are forwardedto the destination LPAR 310 using TSO and using the identified MRU forthe destination LPAR 310 as the transmission unit.

Thus, embodiments of the present disclosure enable better utilization ofvirtual machine bandwidth capabilities by tailoring the packet sizesdestined to MAC addresses of the virtual machines to meet the capacityof the respective virtual machines. For example, embodiments of thepresent disclosure utilize a shared virtual adapter to custom-fit thepacket sizes communicated to a respective virtual machine based on theMRU of the respective virtual machine. The shared virtual adapter isconfigured to perform LRO processing of the incoming data packets basedon the MRU for the virtual machine destination. The aggregated datapackets may then be communicated to the virtual machine destination(e.g., using TSO processing) using the MRU for the respective virtualmachine as the transmission unit.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure. Theembodiment was chosen and described in order to best explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various embodiments with various modifications as are suited to theparticular use contemplated.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

What is claimed is:
 1. A method, comprising: connecting first and secondlogical partitions to a shared virtual adapter, the first logicalpartition having a maximum receive unit (MRU) different than a MRU ofthe second logical partition; responsive to receiving data by the sharedvirtual adapter destined for the first or second logical partitions,performing transmission control protocol (TCP) segmentation offloadprocessing of the data by the shared virtual adapter utilizing the MRUof the first logical partition as the transmission unit for datadestined for the first logical partition and utilizing the MRU of thesecond logical partition as the transmission unit for data destined forthe second logical partition; receiving by the shared virtual adapter anaddress resolution protocol (ARP) response packet corresponding to thefirst logical partition; and identifying the MRU for the first logicalpartition from the ARP response packet.
 2. The method of claim 1,further comprising, responsive to connecting of the first and secondlogical partitions to the shared virtual adapter, identifying the MRUfor the respective first and second logical partitions.
 3. The method ofclaim 1, further comprising including a field in the ARP response packetidentifying the MRU of the first logical partition.
 4. The method ofclaim 1, further comprising aggregating, by the shared virtual adapter,incoming packets of the data up to the respective MRU.
 5. The method ofclaim 1, further comprising storing, by the shared virtual adapter, theMRU corresponding to the first and second logical partitions.
 6. Themethod of claim 1, further comprising disabling large receive offload(LRO) processing of data by a physical adapter.
 7. A method, comprising:receiving incoming data packets by a shared virtual adapter; parsing theincoming data packets to identify a destination address; responsive todetermining that the destination address corresponds to a logicalpartition connected to the shared virtual adapter, determining a maximumreceive unit (MRU) for the logical partition by receiving by the sharedvirtual adapter an address resolution protocol (ARP) response packetcorresponding to the logical partition and identifying the MRU from theARP response packet; setting a data transmission unit for the data tothe logical partition to the MRU for the logical partition; aggregatingthe incoming data packets up to the identified MRU; and performingtransmission control protocol (TCP) segmentation offload processing ofthe data packets to the logical partition utilizing the set transmissionunit.
 8. The method of claim 7, further comprising, responsive toconnecting of the logical partition to the shared virtual adapter,identifying the MRU for the logical partition.
 9. The method of claim 7,further comprising including a field in the ARP response packetidentifying the MRU.
 10. The method of claim 7, further comprisingdisabling large receive offload (LRO) processing of data by a physicaladapter connected to the shared virtual adapter.